Generally, positive photosensitive materials are said to be positively tapered and to have high resolution. As these photosensitive materials, a photoresist obtained from diazonaphthoquinone and novolak resin, and a chemically amplified material using a photoacid generator have been actually used. However, the above photoresist is poor in mechanical strength and electrical characteristics when used as a structural material such as cover insulation material and interlayer dielectric material. Also, as to the chemically amplified material, a photoacid generator is used, thereby making it difficult to use the material in applications requiring electrical reliability.
In order to overcome these disadvantages, the present inventors have previously proposed a positive photosensitive material comprising a 1,4-dihydropyridine derivative and a polyimide precursor resin, and a process for preparing the same (see, for example, Japanese Patent Laid-Open Nos. Hei 05-005995 and Hei 05-281717).
However, in the positive photosensitive material described above, image contrast was low during formation the fixed image at a film thickness of 5 μm or more, and it has been difficult to provide a material having low elasticity.
Accordingly, in view of overcoming these disadvantages, an object of the present invention is to provide a positive photosensitive resin composition having low elasticity, high heat resistance, and high resolution.
These and other objects of the present invention will be apparent from the following description.